In modern commercial vehicles shifting devices are being offered for partial automatic shifting of multi-step, especially multi-step change speed gears of motor vehicles having a clutch situated between the prime mover and the transmission and an electronic control unit for determining admissible shifting recommendations.
For the driver's assistance and to improve the economy when driving with commercial vehicles, especially those equipped with multi-ratio transmissions, several partially automatic shifting devices have been proposed and also developed for dealing with different problems and strategies.
Multi-step transmissions of that kind have as a rule a plurality of power take-off possibilities. Said power take-offs are not only synchronized but claw-clutch engaged. To engage the power take-off, there must be no great difference in the number of revolutions of the claw, since otherwise an undesirable grating noise appears. On the other hand, in case of a difference in the number of revolutions of almost zero, there is great probability of a tooth-on-tooth position of the claws resulting in the power take-off being unable to mesh.